Various sensors for collecting medical information in the human body have been developed and used, herein, not only a technique for collecting information in the human body but also a technique for transmitting collected information to the outside of the human body are very important.
In general data transmitting methods, there is a communication cable method applied to an endoscope which is developed for observing the stomach and intestines. In the communication cable method, a cable made of a conducting wire or an optic fiber is inserted into the human body through throat of the patient. The communication cable method has high reliability and high data quality, however, it may cause severe pain to the patient.
In order to solve the above-mentioned problem, Given Imaging LTD. in Israel has developed a capsule type endoscope called M2A. When a patient swallows the capsule type endoscope like a tablet, video data in the human body photographed by a camera of the endoscope are transmitted to an external-receiving unit, and displayed in a monitor.
However, in the capsule type endoscope, since radio wave is used to transmit a signal, power consumption is large, so that operation time is short, and receiving sensitivity is deteriorated due to interference of various electric waves from the outside of the human body. In addition, radio-transmitting apparatus such as a converter circuit for converting a video signal into a high frequency signal and an antenna for signal transmission, etc. are required, so that volume is increased and production cost is increased. Also, high frequency may be harmful to the human body.